It is proposed to use X-ray and neutron diffraction single-crystal investigations in conjunction with interactive computer graphics, ab-initio quantum mechanical and empirical force-field calculations to study the following problems in carbohydrate chemistry: 1) To compare experimentally the electron density distributions at anomeric and non-anomeric carbon centers in simple carbohydrate molecules and to correlate these results with the theoretical predictions from ab-initioquantum mechanical calculations, 2) To seek to distinguish between the effects of intra-and intermolecular forces in determining the deviations from ideal chair conformations in pyranose sugar molecules in the crystalline state using the methods of molecular mechanics, 3) To develop a molecular mechanics program which is parameterized to fit the neutron diffraction data available from mono-and disaccharides, for use in modelling polysaccharide structures.